Reasons and Evidence: The Provide/Consist Distinction

Recently, while looking in Knowledge and Its Limits, I came across an interesting distinction. The more I thought about the distinction it started to make sense of a topic I’m currently researching—the relationship between epistemic reasons and evidence.

The distinction is: provide vs. consist. Williamson uses this distinction to mention an objection to his view that all evidence is propositional. For Williamson even perceptual experiences, which are often regarded as non-propositional evidence, consist of propositions. An objector might claim: “Experiences provide evidence; they do not consist of propositions” (197, italics mine). However, only propositions we grasp can be used in confirmation, inference to the best explanation, and choice between rival hypotheses. Even though words fail to completely capture perceptual experience it does not mean evidence is non-propositional. Instead, experience makes propositions e1en count as evidence for a hypothesis h. Having an experience bestows the status of evidence on propositions. As such, evidence is inextricably linked to (and mediated by) propositions. Thus, experience consists of propositions.

It is possible to ask the same thing of epistemic reasons and evidence: Are they inextricably linked? There are defenders of two theses concerning this question:

  • Inseparable:  Where you find one you find the other (i.e., reasons and evidence serve the same function, appear under the same analysis, or are constitutionally equivalent).
    • For every proposition p, if p is a reason R then p is evidence E.
  • Separable: Reasons and evidence come apart (i.e., in some scenarios you have reasons but no evidence, and vice versa).
    • There is some p such that p is an R but not an E.

Now I’ll relate this to the provide/consist distinction. One way of arguing for Inseparable is by claiming ‘having’ evidence for the truth of p ‘provides’ you with an epistemic reason for believing p. In response one might argue for Separable by showing evidence for p doesn’t always generate a reason to believe p. A strategy to counter this move is to claim the evidence for p is not really (good) evidence for p. What is taken as evidence for p doesn’t ‘consist’ of evidence; it doesn’t have the status of evidence because its status is undercut by other pieces of evidence.  These moves have the following assumptions:

  • Pro-Inseparable: If you have good evidence for p, then you have a good epistemic reason for believing p.
  • Pro-Separable: Rejects the assumption endorsed by Pro-Inseparable.

Pro-Inseparable claims ‘providing’ sanctions ‘believing’. ‘Believing’ connects to ‘consisting’ in that one is ‘believing’ appropriately if that believing is based on that which has the status (consists) of good evidence (reasons). By transitivity ‘providing’ sanctions ‘consisting’.  A way to argue for Pro-Separable is to show you can have good evidence for p without that evidence grounding a good reason for believing p because the reason is not based on the evidence. As a result, it’s not the case where you have good evidence you always have a good epistemic reason. The epistemic reason needs to be appropriately linked to the evidence to result in ‘believing’ in a way that’s sufficient for the belief to be justified. Simply claiming the two entities are inextricably linked (i.e., where you find one you find the other) doesn’t secure this connection. There’s another way of putting this point.

‘Providing’ focuses on the function of evidence or how it’s used in an argument. Williamson takes this line by arguing evidence ‘is’ (consists) only in so far as it ‘functions’ (provides). For evidence (experience) to play its evidentiary role within an argument it must be propositional. Because experience functionally provides evidence for hypotheses, and evidence must be propositionally grasped in order to be used, experience consists of propositions. Williamson argues for ‘consists’ by way of ‘provides’. The problem with this is that something may ‘consist’ without ‘providing’. I can be justified in believing that p even if no agent has engaged in the activity (function) of justification. This is because p’s status as evidence justifies believing in p in a way that doesn’t depend on anyone having used it in argumentation. It doesn’t require that the evidence is possessed, grasped, or used. That it can only ‘function’ a certain way if it ‘is’ a certain way simply shows that ‘function’ (provide) depends on ‘status’ (consist). It doesn’t show that ‘consist’ can be derived from ‘provide’ when it comes to evidence.

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